diff --git a/Dockerfile b/Dockerfile
index 2d321b3..ade182e 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -57,9 +57,15 @@ RUN git clone --depth 1 https://github.com/ltdrdata/ComfyUI-Manager.git \
 # mask_text parameter). Model weights auto-download on first use into
 # /opt/comfyui/models/{sams,grounding-dino}/ — first inpaint takes ~3 GB of
 # downloads, subsequent runs are instant.
+#
+# Transformers must stay <5: GroundingDINO inside this node calls
+# BertModel.get_head_mask, which transformers 5.0 silently removed. The pin
+# is applied AFTER the requirements install so it overrides anything the
+# upstream requirements.txt would have pulled.
 RUN git clone --depth 1 https://github.com/storyicon/comfyui_segment_anything.git \
         ${COMFYUI_HOME}/custom_nodes/comfyui_segment_anything && \
-    pip install -q -r ${COMFYUI_HOME}/custom_nodes/comfyui_segment_anything/requirements.txt
+    pip install -q -r ${COMFYUI_HOME}/custom_nodes/comfyui_segment_anything/requirements.txt && \
+    pip install -q "transformers>=4.40,<5"
 
 # Entrypoint wrapper — auto-installs requirements.txt for any custom_node
 # present at startup (covers Manager-installed nodes and nodes cloned
diff --git a/install-custom-node-deps.sh b/install-custom-node-deps.sh
index d0d28ab..ebdd1bf 100644
--- a/install-custom-node-deps.sh
+++ b/install-custom-node-deps.sh
@@ -18,4 +18,11 @@ if [ -d /opt/comfyui/custom_nodes ]; then
     done
 fi
 
+# Force-pin known-incompatible packages back into a working range. Some
+# custom nodes bring transformers >=5 transitively, which removes
+# BertModel.get_head_mask and breaks comfyui_segment_anything's
+# GroundingDINO. Run last so it wins over anything the loop above
+# installed.
+pip install -q "transformers>=4.40,<5" || echo "[entrypoint] transformers pin failed — continuing"
+
 exec "$@"